Primary headaches (e.g., cluster headaches, tension headaches, chronic migraines, etc.) are debilitating ailments that afflict millions of individuals worldwide. By definition, a primary headache is idiopathic and non-specific with many possible causes. Examples of possible causes for primary headaches include: trauma, vascular defects, autoimmune deficiencies, degenerative conditions, infections, drug and medication-induced causes, inflammation, neoplastic conditions, metabolic-endocrine conditions, iatrogenic conditions, musculoskeletal conditions, and myofacial causes. While primary headaches can be treated with painkillers to varying levels of success, in many situations, the headache pain can persist post-treatment.
Recent clinical studies in the treatment of headache pain have targeted therapies to the sphenopalatine (pterygopalatine) ganglion (SPG). The SPG is a collection of nerves (e.g., parasympathetic neurons that innervate the middle cerebral and anterior cerebral blood vessels, the facial blood vessels, and the lacrimal glands) located within the pterygopalatine fossa (PPF), a boney cavity deep within the midface. The SPG is a complex neural ganglion with multiple connections (including autonomic connections, sensory connections, and motor connections). One or more of these connections may contribute to the pathogenesis of primary headaches.
Various clinical approaches have been used to modulate the function of SPG for the treatment of primary headaches. These approaches vary from minimally invasive procedures (e.g., transnasal anesthetic blocks) to procedures with greater invasiveness (e.g., surgical ganglionectomy). Other procedures of varying invasiveness include surgical anesthetic injections, ablations, gamma knife procedures, and cryogenic surgery. Although most of these procedures can provide short term relief to the pain of primary headaches (e.g., from days to months), this relief is often temporary.